Apr 17, 2013 1630 UTC Day 1 Convective Outlook | |||||||||||||
Updated: Wed Apr 17 16:35:35 UTC 2013 | |||||||||||||
Probabilistic to Categorical Outlook Conversion Table | |||||||||||||
Public Severe Weather Outlook | |||||||||||||
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The SPC is forecasting ...severe thunderstorms are expected over parts of the southern/central plains later today and tonight.... Please read the latest public statement about this event. View What is a Watch? clip. |
Categorical Graphic | |||||||||||||
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Probabilistic Tornado Graphic | |||||||||||||
Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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Probabilistic Damaging Wind Graphic | |||||||||||||
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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Probabilistic Large Hail Graphic | |||||||||||||
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 171632 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1132 AM CDT WED APR 17 2013 VALID 171630Z - 181200Z ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT FROM NWRN TX THROUGH CNTRL OK INTO SERN KS AND FAR SWRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS INTO TONIGHT FROM PORTIONS OF THE SRN PLAINS INTO THE MIDWEST... ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER PARTS OF KY/TN... ...SYNOPSIS... A POSITIVELY TILTED LONG-WAVE TROUGH FROM THE CANADIAN PRAIRIE PROVINCES TO LOWER CO VALLEY WILL MOVE EWD THIS PERIOD IN RESPONSE TO THE PROGRESSION OF A SERIES OF LOWER-AMPLITUDE PERTURBATIONS THROUGH THE NERN PACIFIC. WITHIN THIS BROADER-SCALE PATTERN...A MIDLEVEL JET STREAK AND ASSOCIATED VORTICITY MAXIMUM WITHIN THE LONG-WAVE TROUGH BASE OVER THE LOWER CO VALLEY WILL REACH THE CNTRL/SRN HIGH PLAINS LATER TODAY INTO THIS EVENING...PRIOR TO MOVING INTO THE MID MO VALLEY BY THURSDAY MORNING. IN RESPONSE TO THESE UPPER-AIR DEVELOPMENTS...A LEE CYCLONE OVER N-CNTRL NM WILL DEVELOP SEWD ALONG AN ASSOCIATED STATIONARY BOUNDARY INTO NWRN TX BY 18/00Z BEFORE ACCELERATING NEWD INTO THE LOWER MO VALLEY BY 18/12Z. THE BAROCLINIC ZONE ATTENDANT TO THIS MIGRATORY CYCLONE WILL LIFT NWD THROUGH THE OZARKS AND LOWER MO/OH VALLEYS AS A WARM FRONT. UNCERTAINTY STILL REMAINS ON THE EXACT LOCATION OF THE WRN EXTENSION OF THIS BOUNDARY OVER THE SRN PLAINS THIS AFTERNOON. CURRENT INDICATIONS ARE THAT IT WILL STRETCH FROM CNTRL THROUGH SWRN OK INTO THE SRN TX PNHDL BY THE 17/21-18/00Z TIME FRAME. A DRYLINE WILL MIX EWD THROUGH WRN TX TODAY...LIKELY REACHING NWRN TX INTO THE TX BIG COUNTRY BY PEAK HEATING. BY TONIGHT...EXPECT THE WRN EXTENSION OF THIS BOUNDARY TO SURGE SEWD ACROSS WRN/CNTRL PARTS OF OK/TX AS A COLD FRONT. ...SRN/CNTRL PLAINS INTO THE OZARKS... 12Z OBSERVED SOUNDINGS SHOWED A POTENT COMBINATION OF RICH BOUNDARY LAYER MOISTURE /I.E. LOWEST 100-MB MEAN MIXING RATIOS OF 13-14 G PER KG/ BENEATH A PRONOUNCED EML WHERE 700-500-MB LAPSE RATES WERE APPROACHING 8.5-9.0 C/KM. WHERE STRONGER HEATING CAN OCCUR...THESE PARAMETERS WILL YIELD A MODERATELY TO STRONGLY UNSTABLE WARM SECTOR BY AFTERNOON WITH MLCAPE VALUES APPROACHING 2000-3000 J/KG. TODAY/S SEVERE WEATHER SCENARIO REMAINS COMPLICATED BY VARYING MODEL SOLUTIONS ON FRONTAL PLACEMENT...AND THE POTENTIAL FOR EARLY DAY STORMS IN CONJUNCTION WITH AN APPARENT WEAK IMPULSE CURRENTLY PROGRESSING NEWD THROUGH THE SRN PLAINS. CURRENT INDICATIONS ARE THAT INITIAL SURFACE-BASED STORM DEVELOPMENT WILL OCCUR LATE THIS MORNING OR EARLY THIS AFTERNOON ALONG THE RETREATING WARM FRONT OVER ERN KS INTO MO. HERE...A RAPIDLY MOISTENING/DESTABILIZING AIR MASS WILL COINCIDE WITH A STRONGLY SHEARED ENVIRONMENT...WHICH WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF VERY LARGE HAIL...TORNADOES /SOME POSSIBLY STRONG/...AND DAMAGING WINDS. SEE RECENTLY ISSUED TORNADO WATCH 114 FOR DETAILS. STORMS MAY GROW UPSCALE INTO CLUSTERS OR LINE SEGMENTS BY THIS EVENING INTO TONIGHT WITH A CONTINUED RISK FOR DAMAGING WINDS...HAIL...AND PERHAPS A FEW TORNADOES. FARTHER SWWD ALONG THE FRONT FROM N-CNTRL OK INTO NWRN TX...STRONGER CAPPING IS EXPECTED TO DELAY STORM INITIATION UNTIL LATER THIS AFTERNOON INTO EVENING WITH THE HIGHEST PROBABILITY OF DEVELOPMENT OCCURRING NEAR THE DRYLINE-FRONT TRIPLE POINT. DESPITE AN INITIAL WEAKNESS IN FORECAST HODOGRAPHS IN THE 2.5-4 KM AGL LAYER...THE ENVIRONMENT WILL BE VERY SUPPORTIVE OF INTENSE SUPERCELLS CAPABLE OF VERY LARGE HAIL AND TORNADOES /SOME POTENTIALLY SIGNIFICANT AND LONG-TRACKED/. AN ENHANCED TORNADO THREAT IS EXPECTED TO PERSIST INTO TONIGHT ALONG THE I-44 CORRIDOR OF OK WHERE HODOGRAPHS WILL GROW INCREASINGLY LARGE AND THE BOUNDARY LAYER WILL REMAIN VERY MOIST AND MODERATELY UNSTABLE. STORMS SHOULD EVENTUALLY CONSOLIDATE INTO A BROKEN LINE ALONG THE SURGING COLD FRONT OVERNIGHT WITH A CONTINUED RISK FOR DAMAGING WINDS...LARGE HAIL...AND A FEW TORNADOES. ...SRN IA/NRN MO/IL INTO TONIGHT... CLUSTERS OF ELEVATED TSTMS ARE ONGOING ACROSS THE REGION WITH ACTIVITY LIKELY BEING FORCED BY LOW-LEVEL WAA/ISENTROPIC ASCENT AT THE TERMINUS OF A 40-50 KT LLJ...AND DCVA ATTENDANT TO A VORTICITY MAXIMUM OVER CNTRL IA /PER RADAR DATA/. EXPECT THESE STORMS TO CONTINUE EWD TODAY WITH AN ASSOCIATED RISK FOR LARGE HAIL AND DAMAGING WINDS. ...PARTS OF KY/TN THROUGH THIS EVENING... REGIONAL RADAR DATA INDICATE STORM REGENERATION OCCURRING FROM CNTRL KY INTO NERN TN...ALONG THE WRN EDGE OF A RESIDUAL COLD POOL ATTENDANT TO A NOCTURNAL MCS. MODIFICATION OF THE 12Z NASHVILLE SOUNDING FOR CURRENT CONDITIONS INDICATES THAT THE AMBIENT ENVIRONMENT IS ALREADY MODERATELY UNSTABLE WITH MLCAPE OF AROUND 2500 J/KG...WHICH SHOULD PROMOTE FURTHER STORM INTENSIFICATION. THIS IS SUPPORTED BY 12Z CONVECTION-ALLOWING MODEL GUIDANCE WHICH DEVELOPS A SWWD/SWD-PROPAGATING MCS ACROSS THE REGION INTO THIS EVENING. THOUGH VERTICAL SHEAR WILL REMAIN WEAK...THE DEGREE OF INSTABILITY WILL FOSTER INTENSE UP/DOWNDRAFTS CAPABLE OF DAMAGING WINDS AND SEVERE HAIL. ..MEAD/LEITMAN.. 04/17/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z |